Carb Rebuild/Accel Pump

[cg2er410]

I have the notorious bog problem ('85 Merc 140 inline 4), but it was livable till the end of the season (Nov). However, the other day, she was acting normal, but after a good run at 3000 RPM for about 15 mins, then followed by about 10 mins at idle speed, I attempted to accelerate and no matter what position I had the throttle, all she did was sound like she was being held back. Once in awhile I could let off the throttle, take her to idle, then slowly give her gas and she would run normal for a few mins then back to the "retarded" or held back sound and performance no matter the throttle setting (I still had about 5 miles to go to get back to my moorings). Safely at the dock, I decided the rebuild could not wait any longer (I have changed all 3 fuel filters, inline, pump and water seperator. Also when I inspected fuel in old filter from seperator, no water in there).<br /><br /><br />So now I have to rebulid, I am a complete rookie, so please forgive what maybe some very stupid questions.<br /><br />I need to rebuild my Merc Carb due to the "bog" problem. I have the kit and the book on how to do this (courtesy of a forum member!). Now on to my stupid rookie questions.<br /><br />1) Can I rebuild while on the boat, meaning do I have to take it off the manifold? I keep the boat in the water, but I can pull it. It is on a creek off the main river with not much wave action.<br /><br />2) Do you use any kind of permatex substance on the gaskets when you replace them?<br /><br />3) If the smarter thing is to pull the carb from the boat, the repair manual says to put the carb in a special "vise" while making the repairs. I don't even have a regular vise! Is this a problem?<br /><br />Any other words of wisdom for a first timer would be appreciated.

 

[Blk-n-Blu]

Re: Carb Rebuild/Accel Pump

Take the carb off the intake!! During a rebuild most mechanics will allow the carb to soak in a parts cleaning solution to remove gum build-up and also use high pressure air to clean the small passages.If you have the kit maybe a local mechanic could do it inexpensively for you. <br />You can't do it on the engine/in the water

 

[mkast]

Re: Carb Rebuild/Accel Pump

It sounds like you have made up your mind the carb needs rebuilding. I hope after you're done the engine doesn't run the same way. Have you completed basic troubleshooting on the engine to eliminate everything else BUT the carb. I'm trying to save you some time.

 

[Rhadley]

Re: Carb Rebuild/Accel Pump

These carbs are very simple. Just keep all the parts organized and note how things go together. I took digital pictures of my carb with all the linkages hooked up before removing it. <br /><br />Vise is suggested to hold it and keep from damaging the bottom and throttle butterfly valves. I just carefully set it on a towel and made sure the valves did not hit the table.<br /><br />The instructions can be confusing regarding how to measure the float levels. Mine showed a dimension from the wrong surface. Also, the dimension had changed. I think Mercarb bulletin 97-08 updated these dimensions-not sure about the number since am at work. <br /><br />No sealer on any gaskets.

 

[Bob_VT]

Re: Carb Rebuild/Accel Pump

Get a plastic tray from a Micky' D's or and luch place. Rebuild the carb on the tray and you will contain the parts. Those little pivot pins love to roll around.<br /><br />Make sure you are getting the right accellerator pump too... it must be designed for the marine use. A regular automotive pump just does not supple the same "big shot" of fuel needed for marine applications.<br /><br />Bob

 

[cg2er410]

Re: Carb Rebuild/Accel Pump

Thanks to all. I think I have done all the other things I should before deciding it was the carb. I have always had the "bog" and spent $ trying to fix it. Had the carb "rebuilt" once before, but unfortunately not by a reputable mechanic I found out later. I have changed plugs, points, condenser, set the points with feeler, going to buy meter to set via dwell to make sure. I have changed all 3 fuel filters I have. I stored the boat gas supply with sta-bil during the winter with a full tank. When I changed the fuel water seperator filter, I did not notice any water in the jar. I have been using the additives for drying your gas and to clean the fuel system.<br /><br />As an aside, I had replaced (coupla yrs ago) the points, etc with after market marine electronic system. Still did the same thing, when I took it to mechanic, he recommended removing the electronic (his opinion, they didnt work well with the older engines) and went back to points, etc. Still had the bog problem either way. When I was reading my Clymers when fitting out, I read about the "Mercarb" bog and the way it was described, that is exactly what my boat has been doing all along and you needed to replace the accelertor pump and a synthetic gasket/flapper or something. It seems that with the newer gas having more alcohol in it than in the past, the older gasket/flapper didnt hold up well to the alcohol content and erroded. The newer pumps and gaskets were made to withstand it better. So I took digital pictures of my carb, learned from here that it was in fact a Mercarb, went to Merc dealer to get rebuild kit. Only issue was which version of accelerator pump I had (naturally Mercarb doesnt make it easy with just one style), and based on the pics, we think we have made the right choice. We'll see when I take it apart.<br /><br />Is there anything else I should check before I take the carb off and rebuild? I joked with my dealer and asked him if they thought I could do the rebuild myself? He said yes, I then asked, you're not setting me up so that when I bring it in it will cost me more are ya..............?